// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_IMPL_H_
#define CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_IMPL_H_

#include <map>

#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/memory_pressure_listener.h"
#include "base/memory/singleton.h"
#include "content/common/content_export.h"

namespace content {

class BrowserChildProcessHost;
class MemoryMessageFilter;
class RenderProcessHost;

// Controller for memory pressure IPC messages. Each child process owns and
// registers a MemoryMessageFilter, which can be used to both suppress and
// simulate memory pressure messages across processes. This controller
// coordinates suppressing and simulation of messages, as well as allows for
// messages to be forwarded to individual processes. This allows the browser
// process to control what memory pressure messages are seen in child processes.
// For more details see content/browser/memory/memory_message_filter.h and
// content/child/memory/child_memory_message_filter.h.
class CONTENT_EXPORT MemoryPressureControllerImpl {
public:
    // This method can be called from any thread.
    static MemoryPressureControllerImpl* GetInstance();

    // These methods must be called on the IO thread.
    void OnMemoryMessageFilterAdded(MemoryMessageFilter* filter);
    void OnMemoryMessageFilterRemoved(MemoryMessageFilter* filter);

    // These methods can be called from any thread.

    // Suppresses all memory pressure messages from passing through all attached
    // MemoryMessageFilters. Any messages sent through a "suppressed" filter will
    // be ignored on the receiving end.
    void SetPressureNotificationsSuppressedInAllProcesses(bool suppressed);

    // Simulates memory pressure in all processes by invoking
    // SimulatePressureNotification on all attached MemoryMessageFilters. These
    // messages will be received even if suppression is enabled.
    void SimulatePressureNotificationInAllProcesses(
        base::MemoryPressureListener::MemoryPressureLevel level);

    // Sends a memory pressure notification to the specified browser child process
    // via its attached MemoryMessageFilter.
    void SendPressureNotification(
        const BrowserChildProcessHost* child_process_host,
        base::MemoryPressureListener::MemoryPressureLevel level);

    // Sends a memory pressure notification to the specified renderer process via
    // its attached MemoryMessageFilter.
    void SendPressureNotification(
        const RenderProcessHost* render_process_host,
        base::MemoryPressureListener::MemoryPressureLevel level);

protected:
    virtual ~MemoryPressureControllerImpl();

private:
    friend struct base::DefaultSingletonTraits<MemoryPressureControllerImpl>;

    MemoryPressureControllerImpl();

    // Implementation of the various SendPressureNotification methods.
    void SendPressureNotificationImpl(
        const void* child_process_host,
        base::MemoryPressureListener::MemoryPressureLevel level);

    // Map from untyped process host pointers to the associated memory message
    // filters in the browser process. Always accessed on the IO thread.
    typedef std::map<const void*, scoped_refptr<MemoryMessageFilter>>
        MemoryMessageFilterMap;
    MemoryMessageFilterMap memory_message_filters_;

    DISALLOW_COPY_AND_ASSIGN(MemoryPressureControllerImpl);
};

} // namespace content

#endif // CONTENT_BROWSER_MEMORY_MEMORY_PRESSURE_CONTROLLER_IMPL_H_
